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# ACE Inhibitors
## Overview
ACE inhibitors (Angiotensin-Converting Enzyme inhibitors) are a class of medications used to treat hypertension and heart failure. They work by blocking the conversion of angiotensin I to angiotensin II, a potent vasoconstrictor, leading to vasodilation and decreased blood pressure.
## Primary Indications
* Hypertension
* Heart failure (HFrEF)
* Post-myocardial infarction (MI)
* Diabetic nephropathy
## Adult Dosing
Dosing is highly individualized and depends on the specific agent, indication, and patient response. Titration is typically required.
* **Hypertension:** Initial doses vary. For example, lisinopril starts at 5-10 mg PO daily, titrating up to 40 mg PO daily. Benazepril starts at 10 mg PO daily, titrating up to 80 mg PO daily.
* **Heart Failure:** Similar starting doses to hypertension, often titrated more slowly. Max doses are generally higher than for hypertension, e.g., lisinopril up to 40 mg PO daily.
* **Post-MI:** Generally initiated within 24 hours of MI if hemodynamically stable. Example: Ramipril 2.5 mg PO BID, titrated up to 5 mg PO BID.
## Pediatric Dosing
Pediatric dosing is less established and often relies on expert consensus or extrapolation from adult data. Dosing is typically based on weight.
* **Hypertension:** Example: Enalapril 0.07-0.1 mg/kg/dose PO q12-24h, maximum 0.5 mg/kg/day or 20 mg/day.
## Dose Adjustments
* **Renal Impairment:** Dose reduction is typically required, especially in patients with severe renal impairment. Specific recommendations vary by agent and creatinine clearance.
* **Hepatic Impairment:** Use with caution. Dose adjustments are not routinely recommended but monitoring is advised.
## Contraindications
* History of angioedema related to previous ACE inhibitor treatment.
* Concomitant use with aliskiren in patients with diabetes mellitus or renal impairment.
* Pregnancy (teratogenic risk).
* Known hypersensitivity to the specific ACE inhibitor.
## Adverse Effects
* **Common:** Cough (dry, persistent), dizziness, hypotension, hyperkalemia, fatigue.
* **Serious:** Angioedema (facial, lingual, laryngeal), acute kidney injury, rash, hepatotoxicity.
## Key Drug Interactions
* **Potassium-sparing diuretics, potassium supplements, spironolactone, eplerenone, salt substitutes:** Increased risk of hyperkalemia.
* **NSAIDs:** May reduce antihypertensive effect and increase risk of renal impairment, especially in volume-depleted patients.
* **Diuretics:** Increased risk of hypotension, especially with loop diuretics.
* **Lithium:** ACE inhibitors can increase lithium levels, potentially leading to toxicity.
* **mTOR inhibitors (e.g., sirolimus, everolimus):** Increased risk of angioedema.
* **ARBs and aliskiren:** Increased risk of hyperkalemia, hypotension, and renal dysfunction. Avoid combination.
## Monitoring
* **Baseline:** Blood pressure, serum electrolytes (especially potassium), renal function (creatinine, BUN).
* **During therapy:** Blood pressure, serum electrolytes, renal function (typically 1-2 weeks after initiation or dose change). Monitor for signs/symptoms of angioedema or hypersensitivity.
## Clinical Pearls
* The characteristic dry cough is dose-limiting for some patients. If cough is problematic, consider switching to an Angiotensin II Receptor Blocker (ARB).
* Initiate therapy at a low dose and titrate slowly, especially in patients who are volume-depleted, on diuretics, or have heart failure.
* Monitor for first-dose hypotension, particularly in patients with high renin levels (e.g., severe heart failure, diuretic therapy).
* Angioedema can occur at any time during treatment and is a medical emergency.
* ACE inhibitors are generally renoprotective in diabetic patients with proteinuria.
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*Disclaimer: This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the most current prescribing information for any medication, as dosing and recommendations can change.*
